Aircraft propeller



May 6,1924. A 1,493,666

v F. CALDWELL ET AL A/IRGRAFT PROPELLER v Filed April 18. 1922 :sheen-sheet 1 j .N I

Malye, 1924. 1,493,066

F. W. CALDWELL ET AL AIRCRAFT PROPELLER Filed April 1a. 1922 Patented May 6, 1924.

' UNITED STATES 1,493,066 ATENT OFFICE.

l FRANK WQQALDWELL AND ERNEST G. MCCAULEY, F DAYTON, OHIO.

AIQRCRAFT PBOPELLER.

J Application led April 18, 1922. Serial No. 554,405.

To all whom t may cof/wem: Beit known that we, FRANK W. CALD- WELL and ERNEST G. MCCAULEY, citizens of the United States, residing, at Dayton, in the county of Montgomery and State of Ohio, .have invented certain new and useful Improvements in Aircraft Propellers, of

which the following is a specification.

The object of this invention is to provide improvements in the art of propellers, especially adapted for use in aircraft, and principally in the construction of same in order to provide a method for relieving the strains set up in the hub, caused by a hammering effect of the engine on the hub due to the uneven and unbalanced inertia forces set up by the engine and its shaft in revolving the propeller. l These unbalanced inertia forces 'cause the propeller to' receive an unevensource of power and these impulses from the engine cause a jerking eect on the propeller, thereby having a tendency to shear the driving keys provided between the engine shaft and the propeller hub. l

' While in the case of a ropeller provided with detachable blades, t e constant hamf mering effect causes the blades to become loose in their mountings in the hub member 30. and thereby throw the propeller out of balance, which when run at high s ed would cause the complete destruction o the engine and probably cause other serious consequences. In some of the present types of engines, especially those of the eight-cylinder t pe, it seems impossible to properly balance t ese inertia-forces, and for this purpose it is proposed to provide a propeller with resillent means for absorbin the hammerin effect of these unbalance inertia forces o the en ne, in sucha manner as to rovide a exi le mounting between the englne and thepropeller hub 1n such a Way as to cause the torque of the blades to act against the resilient means provided in the hub and likewise counteract the unbalanced inertia forces from the engine. 'A designing a propeller of this type, an advent 'e is! gained by using detachable f blades,

be readily replaced andbalanced, thereby 1 prolonging the life of the propeller in service. Also b using a detachable shaft plu v it is possib e to .provide the propeller wi ue'to the fact thata blade may suitable bored shaft plugs Athat would be adapted to fit any type of engine shaft.

With the foregoing and other objects in view, which sha1 appear as the description proceeds, the invention resides in the combinationxof parts and in the details of construction hereinafter described, illustrated and claimed.

Fi re 1 is a horizontal section taken `through the hub assembly of the propeller.,

KVbetween the shaft plug and the hub of the propeller. v

Referring more particularly to the drawings, numeral 1 representsfa hollow ta ered bored engine shaft lplug, vprovided with a plurality of integra splines 5, preferably four in number. Surrounding the shaft plug l isl a .hub l4 having integral reduced extensions 4 -screw-threaded interiorly at 7 to receive pro ller blades 6 which are further secured 1n the hub by means of a bolt 8 passing through the hub and blade and locked by a nut 9 safetied by a cotter key 10. The hub 4 is further provided with splines 3, preferably four in number. Intermediate the shaft plug and hub 4 is arranged a cylindrical layer of tough elastic material 2, such as a phenol condensation product consisting of la ers of cloth or canvas impregnated with akelite, and molded into a solid mass. This member 2 is provided with radial grooves to receive the splines 3 and 5 of the hub 4 and shaft plug 1 respectively.

The member 2 should be of such material having characteristics of toughness, elasticityand resiliency; suliicientl flexible to absorb shock, but rigid enollg shape and osition and not be subject to permanent istortion. The phenol condensation product mentioned has proven satisfactory for the desired purpose but it is appa nt that other materlal having similar charac eristics may be used in Cthis capacity. The shock caused by the transmission of power from the shaft plug 1 to the hub 4 is eiectively taken care of by means of the splines 3 and 5 being embedded in the re'.

silient member 2. y Theprovision lof the Internally Screwto resume its threaded hub makes it possible to replace or mterchange the propeller blades which are adapted to be screwed into the hub eX- tensions and locked therein by suitable re taining means such as bolts and the like.

The shaft plug 1 is screw-threaded at 14 to receive a locking nut 11 and also at 15 to receive a locking nut 12 provided with a washer 13. A retaining nut 16 is screwed onto the reduced threaded portion of the engine shaft 18 for the purpose of holding the hubl on the engine shaft. A locking nut 17 is screwed into shaft plug 1 and abuts against the shoulder 19 of the hub-retaining nut 16 for the purpose of locking same in position. Suitable safety wires 20 and 21 are provided for a purpose which will be readily understood by reference to the drawings. ln Figure 3 is illustrated a modification of the device, the differentiation consisting in the use of compression coil springs in place of and for the same purpose as the phenol condensation product resilient shock; absorbing means.

linA this embodiment a hub 22 is provided with a plurality of of integral splines 23 while the shaft plug 24 has a plurality of integral splines 25. A series of compression coil springs 26 is placed between each spline 23 and its adjacent spline 25. It will be readily seen that the same action takes place as in the previously described mechanism, this embodiment merely consisting in the substitution of compression coil springs for resilient shock absorbing phenol condensation product described.

It will be seen by reference to the foregoin description and illustrations that a Simp e and eil'ective design has been provided for applying a resilient Ameans for revolving the propeller and absorbing or resisting the inertia forces of the engine. However, it is readily realized that a suitable flexible means other than those described hereinbefore may be placed in the propeller hub in such a manner as to give the same results, and it is therefore not desired to limit ourselves to the specific design heretofore submitted, but to claimv broadly the principle of ap lying a resilient means for accomplishing t e above described results.

Having thus described our invention, we claim:

1. In an aircraft propeller, resilient means for revolving said propeller.

. 2. An aerial propeller having a hub and a, plurality of blades, said propeller being provided with resilient means for absorbing andY resistin the unbalanced inertia forces of the shaft om a suitable prime mover for revolving said propeller.

3.v aerial ropeller having a hub and a plurality of bla es, means for revolving said ub and blades, and means for absorbing or` resisting the inertia forces of the shaft "from a suitable prime mover for revolving said iaeacee propeller, said means being arranged be i' tween said prime mover and said hub and blades.

4;., An aerial propeller having a 'hub and a plurality of blades, means for revolving said hub and blades, and means for absorbing or resisting the inertia forces of the shaft from a suitable prime mover for revolving said propeller, said means being arranged between said prime mover and said hub and blades, means for revolving said hub, said last named means consisting of a plurality of splines on the inner side of said hub, said splines being adapted to intermesh with said intermediate resilient member.

5. An aerial propeller having a hub and a plurality of blades, means for revolving said huband blades, and means for absorbing' or resisting the inertia forces of the shaft from a suitable prime mover for revolving said propeller, said means being arranged between said prime mover and said hub and blades, said absorbing means consisting in an intermediate resilient member formed of a phenol condensation product.

6. An aerial propeller having a hub and a plurality of blades, said hub and blades be? ing revolved by a resilient member adapted to absorb and resist the inertia forces of the shaft of a suitable prime mover for revolving said propeller blades, and means for revolving said resilient member.

7. An aerial propeller having a hub and a plurality of blades, said hub and blades being revolved by a resilient member adapted to absorb and resist the inertia forces of the shaft of a suitable prime mover for revolving said propeller blades, and means for revolving said resilient member, said last named means consisting of a shaft plug provided with a plurality of splines adapted to revolve said resilient member.

8. An aerial propeller having a hub and a plurality of detachable blades, said propeller being provided with resilient means for absorbing and resisting the unbalanced inertia forces and means for interchanging said detachable blades.

9. An aerial propeller having a hub and a plurality of detachable blades, said propeller being provided with resilient means for absorbing and resisting the unbalanced inertia vforces and means for interchan ing said detachable blades, said last name means consisting of a threaded portion formed on'the end of said blade and the inner side of said hub, said bladel being screwed into, and adjustably mounted and locked in said hub.

10. An aerial propeller having a hub and a plurality of detachable blades, said propeller being provided with resilient means for absorbing and resisting the unbalanced inertia forces exerted on said propeller, and means forbalancing said blades.

1 1. An aerial propeller having a hub and a Eurality of detachable blades, said propeller 'justably mounted in angular position relaing provided with resilient means for abtive to each/other and likewise correcting, sorblng and resisting the unbalanced inertia the balance of said blades. A 10 forces exerted on sald propeller, and means In testimony whereof we aiix our signa- 5 for balancing said blades, said balancing tures.y

means consistmg of blades bein adapted to FRANK W. CALDWELL. be screwed into or out of said ub and ad- Y ERNEST G. MCCAULEY. 

